Lubricating compositions containing monomeric condensation products of alkylated phenols with carbonyl-containing compounds



LUBRICATING COMPOSITIONS CONTAINING MONOMERIC CONDENSATION PRODUCTS OFALKYLATED PHENOLS WITH CAR- BONYL-CONTAINING COMPOUNDS" Edwin C.Knowles, Poughkeepsie, and John A. Patterson and Herman D. Kluge,Fishkill, N. Y., assignors to The Texas Company, New York, N. Y., acorporation of Delaware No Drawing. Continuation of application SerialNo. 248,654, September 27, 1951, which is a division of applicationSerial No. 178,348, August 8, 1950, now Patent No. 2,734,088, datedFebruary 7, 1956. This application November 23, 1955, Serial No. 548,770

6 Claims. (Cl. 252-52) This invention relates to new monomericcondensation products of substituted phenols with carbonyl compoundswhich have the property of imparting increased oxidation resistance toorganic compounds, and to organic compositions containing them. Moreparticularly, it is concerned with improved lubricating compositionscontaining these monomeric condensation compounds.

It is well known that lubricating oils undergo oxidation in service,particularly under the conditions of temperature and pressure prevailingin internal combustion engines and in modern steam turbines. pounds areformed by this oxidation which cause bearing corrosion and which alsoreact further to form gums and sludges, with rapid deterioration in thelubricating properties of the oil. It is common practice to add tolubricating compositions organic compounds which have the property ofacting as oxidation inhibitors. Among the compounds which have been usedfor this purpose are the phenols, including various alkylated phenolsand phenolic resins.- Many of these compounds are unsuitable because ofan unfavorable effect which they have upon some of the lubricatingcharacteristics of the oil such as viscosity or pour point. A commondifliculty encountered in the use of antioxidants is that they tend toreact chemically with other additives which may also be employed, with aloss in the elfectiveness of either or both of the compounds or evenwith the formation of corrosive or other deleterious compounds. Many ofthe compounds which have been suggested, particularly those of aresinous or polymeric nature, are only diflicultly soluble in oil andhave a tendency to separate out in service. Others have a fairly highsolubility in water or react with alkalimetal compounds which may bepresent in the oil to form water soluble salts, making them unsuitablefor use in oils which become contaminated with water during use.

We have now discovered a class of compounds which are particularlyeffective as oxidation inhibitors. These compounds do not affectadversely the lubricating properties of the oil or react with otheraddition agents commonly employed. They are highly insoluble in waterand in alkaline solutions, so that they are of particular utility incompounding lubricants which are to be used in the presence of water,such as turbine oils.

The compounds of our invention are the monomeric condensation productsof substituted phenols having one available ortho or para position, thatis, one unsubstituted Acidic composition ortho or para to the hydroxygroup, and at least one position ortho to the hydroxy group occupied bya tertiary alkyl group, with carbonyl compounds of the class consistingof aldehydes and ketones. Preferably the condensation product has bothpositions ortho to each hydroxy group either substituted by tertiaryalkyl groups, or one ortho position substituted by a tertiary alkylgroup andthe other involved in the condensation reaction. Thesecompounds may be represented by the following formulas:

OH OH l '12 R R R1 (f- R1 R3 Ra H 0- OH R R R R wherein R is ahydrocarbon radical which may be an alkyl, aryl, alkaryl or aralkylradical, R is a tertiary' alkyl radical, R is hydrogen or an alkylradical and R a hydrocarbon radical such as R. The hydrocarbon radicalsrepresented by R, R R and R may contain any of the usual types ofinorganic substituents such as hydroxy, amino or halogen radicalsinsofar as these do not undesirably affect the characteristics of thecompounds for use in lubricating compositions. In particular R may be asubstituted hydrocarbon radical such as a halogenated aliphatic group ora phenolic group containing at least one and preferably two tertiaryalkyl groups ortho to the hydroxy group. R is preferably an alkylradical containing from 1 to 12 carbon atoms, R is a tertiary alkylradical containing from 4 up to preferably 12 carbon atoms, R ispreferably hydrogen or a methyl radical and R is preferably an alkylradical or halogenated alkyl radical containing up to 7 carbon atoms.

As examples of these compounds the following may be mentioned: 1,1-bis(2-hydroxy-3-tertiary butyl-S- methylphenyl) ethane; 2,2-bis(2-hydroXy-3-tertiary butyl- S-methylphenyl) n-propane;1,3-heXachloro-2,2-bis (2- hydroXy-3-tertiary butyl-S-methylphenyl)n-propane; 1,1- bis (4-hydroxy-3,S-di-tertiary amylphenyl) n-propane;l,1-bis (4-hydroXy-3,S-di-tertiary butylphenyl) n-butane; 1,1-bis(2-hydroxy-3-tertiary octyl-S-methylphenyl) ethane; 1,1-bis(2-hydroXy-3-tertiary butyl-S-methylphenyl) n-butane; 2,2-bis(4-hydroXy-3,S-ditertiary hexylphenyl) propane; 1,1-bis(2-hydroXy-3-tertiary butyl-S-octylphenyl) n-butane; l,l-bis(2-hydroxy-3-tertiary butyl-S- methylphenyl) isobutane; 1,1-bis(Z-hydroXy-S-tertiary amyl-S-methylphenyl) butane; Ll-bis (2-hydroxy-3-tertiary butyl-S-methylphenyl) n-hexane; 1,1-bis (2-hydr0Xy-3-tertiaryamyl-S-hexylphenyl) ethane; 1,1-bis (2- hydroxy-S-tertiarybutyl-S-methylphenyl)-2-trichloroethane; l,l-bis (2-hydroxy-3-tertiarybutyl-5-methylphenyl)- 2-trifiuoroethane; 1,1-bis (2-hydroxy-3-tertiarybutyl-S- .methylphenyl) cyclohexane; 2,2-bis (2-hydroXy-3-tertiarybutyl-S-methylphenyl) n-butane; 2,2'-dihydroXy-3,3'-ditertiarybutyl-5,5'-dimethyl tritane; and 2,2',4"-trihydroxy-3,3 ,3 ,5"-tetra-tertiary butyl-S ,5 -dimethyl tritane.

As previously stated, these compounds are effective antioxidants fororganic compounds generally which tend to undergo deterioration oralteration in thepresence of oxygen. They are of particular utility incompounding mineral oil lubricants which normally undergo consider-Patented Apr. 8, 1958' able oxidation in service with the formation ofacidic compounds and sludges. These compounds greatly reduce thisoxidative tendency in mineral oils when present in the oil even in verysmall amounts. In general it is preferred to add these compounds to theoil in amounts of about 0.01 to about percent,,and usually about 0.1

to 1.0 percent, by weight based on the weight of the oil.

The compounds of our invention may readily be .prepared by carrying outa controlled condensation reaction between a disubstituted phenol havingat least one tertiary alkyl group ortho to the hydroxy group and asuitable aldehyde or ketone. As an alternative method an unsubstitutedor monosubstituted phenol may be condensed with an aldehyde or ketoneunder conditions controlled to give the monomeric condensation productand this product alkylated to give the desired compound. Because of thedifficulty in controlling condensation reactions involving formaldehydeit is preferred to employ aldehydes containing at least two carbon atomsto the molecule. With. aliphatic aldehydes containing more than about 7carbon atoms and with higher aliphatic ketones the condensation reactionproceeds only with difficulty, so that the preferred reactants of thisclass are the lower aliphatic ketones, aliphatic aldehydes containingfrom, 2 to 7 carbon atoms to the molecule and aromatic aldehydes.Suitable compounds include acetaldehyde, chloral,

butyraldehyde, iso-butyraldehyde, benzaldehyde, salicyl-' aldehyde andacetone. When the aldehyde or ketone employed in the condensationcontains a phenolic group, this group should have at least one, andpreferably two, tertiary alkyl groups ortho to the hydroxy group, .orsuch groups may be introduced by alkylation after the condensationreaction.

According to the preferred method for producing these compounds, twomols of a suitable disubstituted phenol is reacted with one mol of analdehyde or a ketone of the type described above in the presence of HClas a catalyst. The reaction may be carried out in the cold in thepresence of a solvent such as glacial acetic acid, or in some casesimproved results are obtained by operating in the absence of a solventand at room temperature. As an example of this method,1,l-bis-(2-hydroxy-3- tertiary butyl-S-methylphenyl) n-butane wasprepared in yields as high as 93 percent of the theoretical by reacting4-methyl-2-tertiary butyl phenol and n-butyraldehyde at room temperatureand without a solvent in the presence of anhydrous HCl as a catalyst. Asanother example of the method, 2,2'-dihydroxy-3,3'-di-tertiarybutyl-5,5-

dimethyl tritane was prepared in a 43 percent yield by reacting4-methyl-2-tertiary butyl phenol and benzaldehydc in the presence ofanhydrous HCl as a catalyst and of glacial acetic acid as a solvent,while the mixture was cooled in an ice bath. As a further example of themethod of preparing these compounds, .l,l-bis (2-hydroxy-3-tertiarybutyLS-methylphenyl)-2-trichloroethane was prepared in a 76 percentyield by reacting 4-methyl-2- tertiary butylphenol with chloral at roomtemperature and without a solvent in the presence of anhydrous HCl as acatalyst.

A number of compounds were prepared by the above described method andtheir efiectiveness as oxidation inhibitors. evaluated by means of theASTM turbine oil oxidation test. This test is carried out by bubblingoxygen through a sample of oil in the presence of water and of spiralsof iron and of copper in an oxidation cell which ismaintained at 95 C.Portions of the oil arewithdrawn periodically and the neutralizationnumber determined. The test is continued until the neutralizationnumberof the oil reaches 2.0.; Table 1 below shows the results obtainedby adding small amounts of typical compounds of our invention to areference oil, which was a solvent-refined, acid-treated and filteredmineral lubricating oil having a Saybolt viscosity of 485-515. secondsat 100 F.

Table l Neutrali- Hours to zation 2.0 neunumber of tralization blendednumber oil Reference oil Q. 75 Reference oi1+0.2% of 1,1-bis(2-hydroxy-3- tertiary butyl-5-1nethylphenyl) ethane 0. 02 200 Reference0il+0.6% ,of 1,1-bis (2-hydroxy-3- tertiary butyl-5-methylphenyl) ethaneO. 08 400 Reference sill-0.2% of 1,1-bis (Z-hydroxy-3- tertiarybutyl-5-methylphenyl) isobutanc- 400 Reference oil+().5% of 1,1-bis(2-hydroxy-3- tertiary butyl-5-mctl1ylphcnyl) isobutane- 825 Referenceoil+0.2% of 1,1-bis (2-hydroxy-3- tertiary butyl-E-methylphenyl)n-butane 375 Reference 0il+0.4% of 1,1-his (Z-hydroxytertiarybutyl-5-methylpheny1) n-butane 500 Reference oil+0.6% of 1,1-bis(2-hydroxy-3- tertiary butyl 5 methylphenyl) 2 trichloroetha'ne 432Reference oil+0.3% of 2,2-dihydroxy-3,3-t1itertiary butyl-5,5"dimethyltritane Reference oil+0.5% of 2,2-dihydroxy-3,3d1-

tertiary butyl'5,5'-dimethyl tritane 200 The above'data show that all ofthe compounds tested imparted a substantial improvement in the oxidationstability of the base oil.

Additional tests were carried out on our compounds in oils containingother addition agents which have been used in compounding lubricants. Itwas found that the efiectiveness of our compounds as oxidationinhibitors was greatly enhanced in the presence of certain of theseother addition agents, namely the class of compounds comprisingoil-miscible organic phosphates and the class of compounds comprisingoil-miscible alkyl dicarboxylic acids as disclosed in U. S. Patent No.2,452,321. The improvement obtained by the use of these compounds inconjunction with the compounds of our invention was much greater inevery case tested than the mere sum of their separate effects, and thisresult is not predictable on the basis of the chemical nature of theindividual compounds. This property of our compounds in actingcooperatively with these other antioxidants and corrosion inhibitors isof great importance, particularly in the compounding of turbine oils,where the use of corrosion inhibitors is necessary to prevent rusting ofthe metal surfaces by the water which contaminates the oil, andaccordingly lubricant compositions comprising our novel compoundstogether with these other compounds is a preferred embodiment of ourinvention. The organic phosphates employed are oil-soluble or misciblealkyl acid phosphates and'preferably those having a total of at least 10alkyl carbon atoms containing at least one replaceable hydrogen linkedto the phosphorus through an oxygen atom. Examples of the type ofcompound falling within this classification which have been foundsatisfactory for use in the inhibitor combination are the followacidsemployed in the combination may be any oil-soluble or miscibledicarboxylic acids having at least one carbon atom between the carboxylgroups and preferably those having at least 10 carbon atoms in themolecule. Such acids include the derivatives of aromatic dicarboxylicacids, cycloaliphatic dicarboxylic acids and aliphatic dicarboxylicacids. As examples of such compounds may be mentioned alkylated phthalicacid, alkylated hexahydrophthalic acid, alkyl malonic acid, alkyl maleicacid, alkenyl' succinic acid and alkyl citraconic acid. A preferredmaterial of this character is obtained by condensation of maleic acidanhydride and a polymer gasoline distillate, B. P. 385-400" F. Forconvenience this material is designated as AMA in the followingdisclosure.

Table 2 below shows the results obtained by using our compounds inconjunction with small amounts of AMA and O-l62 in the ASTM turbine oiloxidation test described above, and also in a modified ASTM rusting testusing synthetic sea water. In this latter test a polished steel specimenis suspended in an agitated mixture of 300 cc. of the oil to be testedand 30 cc. of a synthetic sea water, maintained at 140 F. After 48 hoursthe steel specimen is removed, washed with precipitation naphtha orhexane and the amount of corrosion or rust observed. The synthetic seawater added to the test oil contains 11.0 g. per liter of magnesiumchloride (MgCl -6H O), 1.2 g. anhydrous calcium chloride (CaCl 4.0 g.anhydrous sodium sulfate (Na SO and 25.0 g. sodium chloride (NaCl). Thebase oil used in this test was the same as that used in the ASTM turbineoil oxidation test.

Table II Neutral- Hours to ization 2.0 neu- Busting Additives number oftralizatest blended tlon 011 number 0.015% AMA+0.0025% -162 150 clean.0.5% 1,1-bis (2-hydroxy-3-tertiary butyl- 5-methylphenyl)isobutane+0.016%

AMA+0.0025% 0-162 1, 390 Do. 0.2% 1,1-bis (2-hydroxy43-tertiary butyl- 5methylphenyg n butane 0.01%

AMA+0.0025% 162. 0. 06 650 D0. 0.3% 1,1-bis (2-hydroxy3-tertiarybutylfi-methylphenyl) n butane+0.015%

AMA+0.0025% 0-162 0. 04 1, 000 D0. 0.4% 1, l-bis (2-hydroxy-3-tertiarybutylfi-methylphenyl) n butane+0.015%

AMA+0.0025% O-162 1, 290 a Do. 0.2% 4 methyl 2,6 di tertiary butylpheno1+0.01% AMA+0.0025% O162.. 0. 09 470 D0. 0.5% 4 methyl 2,6 ditertiary butyl phen0l+0.01% AMA-j-o.0025+ O-lfil. 0. 05 880 Do.

As can be seen from the above table, the addition of small amounts ofour compounds to a lubricating oil together with small amounts of AMAand O-l62 pro-.

duces a lubricating composition having substantially greater oxidationstability than an oil containing like amounts of AMA, O-162 and2,6-di-tertiary butyl-4-methyl phenol, which is generally rated as avery effective antioxidant.

It is to be understood that the invention is not limited to the specificexamples mentioned above, but also includes other compositionscontaining compounds falling within the scope of our invention as setforth in the specification and claims. Other additives of the typecommonly employed as lubricant additives such as oxidation inhibitors,pour point depressors, oiliness agents, color stabilizers, extremepressure agents, V. I. improvers, etc., may be used in conjunction withour novel compounds instead of or in addition to the oilmiscible organicphosphates and dicarboxylic acids disclosed specifically.

This application is a continuation of our co-pending application SerialNo. 248,654, filed September 27, 1951, now abandoned, which is adivision of our co-pending application Serial No. 178,348, filed August8, 1950, now U. S. Patent No. 2,734,088.

Obviously many modifications and variations of the invention, ashereinbefore set forth, may be made Without departing from the spiritand scope thereof, and therefore only such limitations should be imposedas are indicated in appended claims.

We claim:

1. A lubricant composition comprising a major amount of a minerallubricating oil and 0.1 to 5.0 percent by weight, suflicient to conferantioxidant properties to the composition, of a compound selected fromthe class consisting of 1,1 'bis (2 hydroxy 3 tertiary butyl 5-methylphenyl) n butane, 1,1 bis (2 hydroxy 3 tertiary butyl 5methylphenyl)isobutane and 1,1 bis (2 hydroxy 3 tertiary butyl 5methylphenyl) 2- trichloroethane.

2. A lubricant composition comprising a major amount of a minerallubricating oil and 0.1 to 5 percent, and preferably 0.1 to 1 percent byweight of 1,1-bis(2-hydroxy- B-tertiary butyl-5-methylphenyl) n-butane.

3. A lubricant composition comprising a major amount of a minerallubricating oil and 0.1 to 5 percent, and

preferably 0.1 to 1 percent, by weight of 1,1-bis(2-hydroxy-3-tertiarybutyl-S-methylphenyl) isobutane.

4. A lubricant composition comprising a major amount of a minerallubricating oil and 0.1 to 5 percent, and preferably 0.1 to 1 percent,by weight of 1,1-bis(2-hydroxy-3-tertiarybutyl-S-methylphenyl)-2-trichloroethane.

5. A lubricant composition comprising a major amount of a minerallubricating oil and in combination therewith 0.01-3.0 percent by weightof an oil-miscible alkyl dicarboxylic acid containing at least 10 carbonat oms, 0.0001-5 .0 percent by weight of an alkyl acid phosphatecontaining at least 10 alkyl carbon atoms, and 0.1- 1 percent by weightof 1,1-bis (2-hydroxy-3-tertiary butyl- S-methylphenyl) butane.

6. A lubricant composition comprising a major amount of a minerallubricating oil and in combination therewith 0.013.0 percent by weightof an oil-miscible alkyl dicarboxylic acid containing at least 10 carbonatoms, 0.00015.0 percent by weight of an alkyl acid phos phatecontaining at least 10 alkyl carbon atoms, and 0.l-1 percent by weightof a 1,l-bis(Z-hydroXy-B-tertiary butyl-S-methylphenyl) isobutane.

References Cited in the file of this patent UNITED STATES PATENTS2,017,827 Bannister Oct. 15, 1935 2,202,877 Stevens June 4, 19402,270,959 Murke Jan. 27, 1942 2,295,985 Baird Sept. 15, 1942

1. A LUBRICANT COMPOSITION COMPRISING A MAJOR AMOUNT OF A MINERALLUBRICATING OIL AND 0.1 TO 5.0 PERCENT BY WEIGHT, SUFFICIENT TO CONFERANTIOXIDANT PROPERTIES TO THE COMPOSITION, OF A COMPOUND SELECTED FROMTHE CLASS CONSISTING OF 1,1 -BIS(2-HYDROXY-3-TERTIARYBUTYL-5METHYLPHENYL) N-BUTANE, 1,1-BIS(2-HYDROXY 3TERTIARYBUTYL-5-METHYLPHENYL)ISOBUTANE AND 1,1-BIS (2-HYDROXY-3-TERTIARYBUTYL-5-METHYLPHENYL)-2TRICHLOROETHANE.